Are CT scans safe? Is it true that CT scans may increase my risk of cancer?

Answers from Cynthia H. McCollough, Ph.D.

Medical imaging exams — including CT scans — have been directly linked to greater life expectancy and declining cancer death rates. Medical imaging exams are also generally less expensive and safer than invasive procedures, such as exploratory surgery.

Like other X-ray-imaging exams, CT scans expose you briefly to a small, targeted amount of ionizing radiation, which helps create an image of structures inside your body. CT scans provide more-detailed images of more types of tissue than traditional X-rays do, which allows your doctor to detect and locate many medical conditions.

CT scans have various purposes. They include helping to diagnose a condition, guiding medical procedures, such as needle biopsies, and monitoring the effectiveness of certain treatments, such as cancer treatments.

At the low doses of radiation a CT scan uses, your risk of developing cancer from it is so small that it can't be reliably measured. Because of the possibility of an increased risk, however, the American College of Radiology advises that no imaging exam be done unless there is a clear medical benefit.

Doctors are encouraged to use the minimal radiation necessary when performing imaging exams. If your doctor recommends a CT scan, ask about the potential benefits to your health, which generally greatly outweigh any small potential risk from radiation.

Legal Conditions and Terms

Reprint Permissions

A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.org," "Mayo Clinic Healthy Living," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.